1. Field of the Invention
This invention relates to a clip, which is used to clip a stack of business paper sheets or like loose sheets and permits quick unclipping to separate the paper sheets when necessary.
2. Description of the Prior Art
Extensive use has previously been made of clips commonly termed Gem clips or V-shaped clips, each of which comprises inner and outer clamping loops formed to protrude forwardly in a U- or V-shaped form. In these clips, the inner and outer clamping loops lie in the same plane. Therefore, even when clipping a very thin sheet stack, the two loops are displaced from each other by at least the thickness of a wire. As a result, an adequate clipping force is produced. Further, with these clips, there is no distinction between the front and back sides, and the inner loop may be displaced from either side of the outer ring. Therefore, even if the inner loop becomes permanently displaced from one side of the outer loop, the clip is reusable with the inner loop on the other side of the outer loop.
Other clips which consist of wires include those shown in Japanese Utility Model Publication No. 366551, Japanese Utility Model Publication No. Showa 52-31512 and paper clips shown in U.S. Pat. No. 4237587. These clips have elongate overlapped clipping portions between opposing loops so that material is clipped. Since the material is sandwiched between overlapping loops, it need not be deformed, and no trace of the clip appears.
In contrast, with the aforementioned Gem clip or V-shaped clip, the inner and outer loops lie in the same plane and do not overlap. When the material is clipped, the inner loop forces the material through the center of the outer loop. Therefore, there is a possibility of bending the end of the clipped material. This drawback is particularly apparent when clipping a thin and soft material. A recess-like trace of clipping is left on the surface of the clipped material. This drawback has been pointed out from an early date, and various improvements have been proposed.
Clips shown in the Japanese Utility Model Publication No. 366551 disclose clipping the material between overlapped loops, however it is difficult to use these clips in the converse form. Besides, it is difficult to manufacture the clip so that the legs of the loops (consisting of a thin wire) are held in close contact with each other. This often results in an inadequate clipping pressure. Also, there is inevitably a loosening of the close contact. Consequently, there is a possibility that sufficient clipping force can not be obtained when clipping a sheet stack consisting of a small number of sheets.
Further, when the overlapped leg portions are separated by plastic deformation in clipping a thick material, their initial state can not easily be restored. Therefore, the clip is not well suited for clipping important documents, and can be used again only with difficulty.